Avengers: Endgame became good at his own name and delivered a ton of endings – and most of them were actually excellent, if tragically, satisfying the conclusions of a decade of work. However, one of them was not.
And very soon it destroyed the entire film.
Think about this warning on your spoiler.
Steve Rogers finished his term as the main hero of the MCU by not only using Mjolnir and surviving a really brutal thang of Thanos, but also (apparently) volunteering to be the person who will return the endless stones back to their respective points in the timeline. You know, in order to avoid all the time-scales that have been warned by the Antique Bruce Banner with their helpful cosmic infographics. Steve does this for himself alone for some reason, which also does not make much sense, but we will leave that slide for now.
The real problem is that Steve actually failed in his mission. He returns the stones back, surely, and returns Mjolnir who uses it to Asgard, obviously, but then he decides to bypass and live a full life with Peggy Carter sometime in the past. This results in the fact that he appeared in the present not by taking the quantum portal, but by walking (or maybe he took Uber? Who knows) on a bench some 50 meters to the left of the portal, returning as an old man who lived his whole life in blink the eye of the audience.
We even got a bit of Flashback on Steve, he finally shared his dance with Peggy in the 40's (or maybe the 50's, after the war) in what is obviously intended to be a very romantic, fulfilling code of his story.
Or, perhaps, it would be if he even worked on Steve's theme arch during his mandate at the MUU or according to the rules he himself established.
Getting technical with time travel
Let's first consider the logic of the time-ending of Endgame. As explicitly stated, with your own rules of Endgame, you can not change the present, you can only create new time limits – i.e. If the endless stones were not returned to the exact places at the exact moments from which they were taken, the MCU will deal with a bunch of branching timeframes, where different characters and whole films could either not exist or be completely doomed. Several of these branched time frames definitely still exist – the alternative 2014 when Thanos brought his forces to Earth years earlier than he initially did, an alternate 2011 when Loki escaped with Thessaract after the end of the Avengers 1 and so – but those for whom he was caring, were treated by Steve. That was his mission.
But, in the process of closing all potential branches, Steve apparently made a new one. Or, on the contrary, he had to make a new one, but somehow not. Steve changed his past, and Peggy Carter's past by attending those 70 years, initially passed frozen and married to her – which, for whatever reason, allowed him to exist as an old man in the main timeline that he abandoned – our presence.
If Steve actually created a branched timeframe, he would not be an old man in the present. His reformed existence in the past was to change events to the extent that today's film day will be different not only for Steve, but for everyone. All together we will see a different time frame.
In the interest of mitigating the confusion here (and make no mistake – this is confusing as hell) to break it. There are two potential opportunities.
The possibility 1 is that Steve has made an alternative timeframe for which we could never see where he and Peggy got married, maybe they went out and were superheroes together, stopped HYDRA from infiltrating SHIELD, rescued Bucky, preventing the assassination of Howard Stark and denying the need for Avengers completely. In that process, he wiped out the whole life he knew Peggy had had, including her husband and the children she had while in the ice. Puff, no.
Then, happy and old, Steve miraculously jumped on our timeframe without placement, which should be impossible, and without a real reason, just in time to pass the shield against Sam. Seriously, why would I be struggling to return at all if he is so confident that he does not need him anymore in today's world? Why did he leave the timetable, especially if it really was so much better? What stimulus must go through problems?
What is Option 2?
Opportunity 2 is that Steve did not create a branched time frame by going back, living his life that is quiet in the post-war years. It will make him an accomplice in knowing all the terrible things that happen to the people he loves during those years. This would also mean, in order not to cast a baseline time frame, that our version of Steve was always married to Peggy, even if he did not know it until this moment. This not only contradicts the overall television show of Agent Carter and various parts of the MCU up to now (as Steve perceives when Pigeon dies after divorce), it also means that Steve will be Sharon Carter's uncle – and, Wow, it's pretty gross, even if he did not know it at the time.
Even by rejecting the potential for a sloppy incest, there are other major problems. Do you remember when Steve said that when he sees the situation in the south, he can not turn his back? I remember how Steve's whole story was born about his inability to sit back and allow a conflict to pass its way without him? How does he love the thugs, no matter where they are? How does he literally undergo a potentially deadly scientific experiment instead of not fighting the war? How did he jump on the German occupied territory without an army that supported him precisely because of the chance that he had something he could do to help his friend? How can he "do it all day?" They started a war to clear the name of his former assassin? He still acted as a hero even while he was an international refugee?
In which world Steve Rogers, even beaten and laughed Steve Rogers, just sit on his hands and let the future handle his own problems?
The answer should not be one of them.
This does not even start to publish another unpleasant topic. The people who came back from Snap were literally fallen in the future when there was no time – a miniature version of Steve's experience that woke up from the ice in 2011. But, apparently, he is quite right by simply digging the world experiencing a level of trauma that he is uniquely qualified to help through.
"He earned the right to be selfish!" You say? Of course. If someone deserves a rest, it's Steve – but that does not mean he will take it. We spent the last 8 years studying the films of this character, and in the last 7 decades we met him in the comic book. To allow something to happen, fundamentally, it is not something he would do. It just is not. He can retire, hand over Sam's shield and take a big step back, but there's no way Steve can give up the fight completely – and this literally happened in the comics. Steve is even an old man, but he still does not stop participating in the superhero world. It's just not in his nature to give up – it would be like Tony suddenly deciding not to be the only hell engineer.
But say that the stupid, esoteric logic of travel for travel does not matter to you anyway – there is still a problem. It is less related to mechanics and more closely related to Steve's place in the meta-narration of the MCU.
Let's ignore travel time all along
For a second, let's pretend that we do not have almost 100 years of comics to watch and focus exclusively on the 60-odd hours of the movie that was given to us. Topically, Steve is a man who has lost a lot in these films. Probably, this is his most prominent quality – he went to ice 70 years ago and thinks another man comes out – his words, not mine. The motive can not go back home again and again and again and again – and through all this, Steve learned how to proceed. And that's a good thing – or at least it was a good thing. With the progress, Steve actually did exactly what Peggy Carter was hoping for him ("The world has changed, and none of us can come back. What we can do is best, and sometimes the best we can do is to start ".)
Of course, there are several punches in Endgame, where it seems to finally hit its breaking ("some people are moving, but not we"), but that just means that he was beaten, not taken out. Hell, he even manages to call for the will of the will to be at the eleventh hour worthy of using Mjolnir, which makes only the third character and only a mortal in the MCU to do so. It's nothing to scoff.
Steve can be defined with a loss, but the power of his character comes from turning that loss into effect. Of course, he is a super soldier, he is quick and strong, and can take on great beatings, but his real superpower is his indomitable will. If there's one thing you can think of in the world, Captain America will not give up, even when things are in their absolute position.
Except when you do, obviously. Giving Steve as a time card without exit from prison can seem like a good idea on the surface, but at the end of the day it all repeats his whole journey. What is the point of highlighting the Everlasting Movement Machine, which is Steve Rogers – constant assurance that no matter how dark things are, no matter how much you lose, you can still move forward – if the ultimate reward is to do exactly something it was said that he could not do; that he spent his life and five films moving away?
It does not mean anything for a completely spent payment for every moment of his solo trilogy. Do you remember how important his "I am with you to the end of the line" to restrain yourself with Bucky Barnes? I hope you do – there is officially licensed goods with that line printed on it. Fans tattooed their bodies. It's coming many, and for good reason. It was not quite subtle as far as big symbolic gestures were concerned and it was a major part of not one, not two, but three individual films. Funny as it is now more like "I'm with you to the right moment when I decide that I do not want to hold up anymore." Funnier however as that line, perhaps the most memorable Captain America line of the entire MCU to "I can do this all day" – another thing that, apparently, is not true – it does not get any shout or call back in a movie that's about 90 % cry outs and call back on memorable MKS moments.
It is cheap, not romantic, and unnecessarily dull edge of an otherwise powerful arc. The lesson to deal with grieving and turning to the future has become a relentlessly lubricated leg of a return to the past, with Steve's trip no longer related to the recovery process; it is a message of real work to you " wonderfully presented with a magic bullet to make all your hard work and effort no longer matters.
Which, frankly, sucks.
And, indeed, none of this is even touching the fact that the connection of the level of Steve and Peggy with regard to the level of the soul was prompted over what, like a week ago in 1945? Perhaps he was supposed to get it. She definitely does not. There was a whole TV show about it.
Both of them deserved much better.